[RE-wrenches] Fw: Xantrex C-40 Drifting

Howie Michaelson howie at suncatchervt.com
Thu May 21 13:02:27 PDT 2015


At the risk of adding more confusion to this conversation, I thought I'd
mention something that may be completely unrelated. This would possibly
pertain to this issue if there is a Trace TM500 in the system.

Many years ago, I made many trips to an off-grid site with an SW5548, C40,
and the old Trace TM500 meter, due to the C40 reportedly not working. 
After not seeing the problem on several trips, I finally saw the C40
behave erratically and shut-off for significant periods.  I cannot
remember the exact scenario which caused the problem, but it was directly
related to the TM500's circuit board which was bolted to the shunt. 
Apparently this circuit board created enough noise that it confused the
C40 and shut it off.  At the time, Xantrex did not "know" of any problem
related to this, but talking with Ralph Hiesey at Bogart Engineering (who
had sold Xantrex the design for the meter), he said that he had cautioned
Trace to not split the circuit board up and place it on the shunt, for the
reason that it would put unwanted noise into the system.  This was
apparently only caused trouble in 48volt systems. Xantrex eventually
admitted that there was some internal research being done on the issue and
they had only known about it for the previous 6 months!  I believe that
was the "support" incident that convinced me to not use Xantrex equipment
anymore - fortunately, by then we had Outback as an alternative to move
to...

This is obviously different than the issue at hand, but just thought I'd
mention the history in case there was something similar going on.

Howie
-- 
Howie Michaelson
NABCEP Certified PV Installation Professional™

Catamount Solar, LLC
Renewable Energy Systems Sales and Service
VT Solar Electric & Hot Water Incentive Partner
http://www.CatamountSolar.com
802-272-0004


On Thu, May 21, 2015 3:07 pm, boB at midnitesolar.com wrote:
>
>
> The old 48V SW inverter, designed by the same person (Greg) that designed
> the C-40, C-12, C-6 and C-60 only has a 0.4 volt resolution.  Does the
> C-series
> CC's also have this resolution ?  Maybe that's why you might see a +-0.2
> or 0.3 volt
> variation ?  Not that big of a deal usually for a 48V battery.
>
> That circuit, like most PWM chargers, regulate the "average" DC battery
> voltage so some
> peak and valley voltages are going to happen.
>
> boB
>
>
>
> On 5/21/2015 9:47 AM, Jarmo.Venalainen at schneider-electric.com wrote:
>> Hi:
>>
>> The C40 circuit is a really simple circuit made up of a set of
>> resistors, capacitors, op-amps, a time-base crystal and PWM.  Simple
>> electronic components, so I don't see drift issues, except maybe under
>> large temperature changes.
>>
>> What does change a lot is the intensity of the sun and thereby the
>> Voc, Vmp, Imp, etc. of the module/array.
>>
>> Given that the PWM applies the varying "raw" available array
>> voltage/current directly to the battery, I think that's how the output
>> voltage variation issue arises.
>>
>> It's an idea.  It may be right or wrong.  Some trials would be needed
>> to prove or disprove it.
>>
>> JARMO
>> _____________________________________________________________________________________
>> *
>> Jarmo Venalainen*  | *Schneider Electric **|  Xantrex Brand*  |
>> *CANADA*  | *Sales Application Engineer* *
>> Phone:* +604-422-2528  | *Tech Support:* 800-670-0707  | *Mobile:*
>> +604-505-0291 *
>> Email:* _jarmo.venalainen at schneider-electric.com_
>> <mailto:jarmo.venalainen at schneider-electric.com> |
>> *Site:*_www.Xantrex.com_ <http://www.xantrex.com/> | *Address:* 3700
>> Gilmore Way, Burnaby, BC V5G4M1
>> <http://www.xantrexrebate.com/>
>> <http://www.xantrex.com/> 	<https://www.facebook.com/Xantrex>
>> <https://twitter.com/Xantrex> 	<https://twitter.com/Xantrex>
>>
>>
>>
>>
>> *** Please consider the environment before printing this e-mail
>>
>>
>>
>> From: 	Steve Bell <sbell at morningstarcorp.com>
>> To: 	RE-wrenches <re-wrenches at lists.re-wrenches.org>,
>> Date: 	05/21/2015 09:25 AM
>> Subject: 	Re: [RE-wrenches] Fw: Xantrex C-40 Drifting
>> Sent by: 	"RE-wrenches" <re-wrenches-bounces at lists.re-wrenches.org>
>>
>>
>> ------------------------------------------------------------------------
>>
>>
>>
>> Hello Wrenches,
>>
>> I have been following this C-40 drifting thread. From my personal
>> experience the C-40 always had about a 0.2 to 0.4 volt drift since the
>> early days (1994-95). This was on a 48-volt system, so the drift might
>> be less at lower battery voltages. The drift was not a simple
>> mis-calibration; one day 0.3 volt high, another day 0.4 volts low.
>> I don't know if this is a component of the problem, but thought I
>> would mention it.
>>
>> Best Regards,
>>
>> Steve Bell
>>
>>
>>
>>
>> On Wed, May 20, 2015 at 7:34 PM,
>> <_Jarmo.Venalainen at schneider-electric.com_
>> <mailto:Jarmo.Venalainen at schneider-electric.com>> wrote:
>> Hi:
>>
>> My thought is that the mechanism by which the battery voltage slowly
>> rises under the influence of a solar module connected through a C40
>> type PWM controller is due to the fact that the PWM type controllers
>> don't regulate voltage but rather connect the full output voltage of
>> the module/array to the battery on a pulse width limited basis.
>>
>> Seems that those high voltage pulses, brief as they may be thanks to
>> the PWM, are still none the less able to slowly raise the resting
>> terminal voltage of at least some types of AGM batteries.
>>
>> I don't know enough about batteries to know if that is a problem or
>> not. Perhaps its perfectly normal as almost any new lead acid battery
>> will retain a higher than normal measurable "ghost voltage" just after
>> it has been fully charged.
>>
>> JARMO
>>
>>
>> _____________________________________________________________________________________*
>>
>> Jarmo Venalainen*  | *Schneider Electric **|  Xantrex Brand*  |
>> *CANADA*  | *Sales Application Engineer* *
>> Phone:* _+604-422-2528_ <tel:%2B604-422-2528> | *Tech Support:*
>> _800-670-0707_ <tel:800-670-0707> | *Mobile:* _+604-505-0291_
>> <tel:%2B604-505-0291>*
>> Email:* _jarmo.venalainen at schneider-electric.com_
>> <mailto:jarmo.venalainen at schneider-electric.com> |
>> *Site:*_www.Xantrex.com_ <http://www.xantrex.com/> | *Address:* 3700
>> Gilmore Way, Burnaby, BC V5G4M1
>> <http://www.xantrexrebate.com/>
>> <http://www.xantrex.com/> 	<https://www.facebook.com/Xantrex>
>> <https://twitter.com/Xantrex> 	<https://twitter.com/Xantrex>
>>
>>
>>
>>
>>
>> *** Please consider the environment before printing this e-mail
>>
>>
>> From:	Drake <_drake.chamberlin at redwoodalliance.org_
>> <mailto:drake.chamberlin at redwoodalliance.org>>
>> To:	RE-wrenches <_re-wrenches at lists.re-wrenches.org_
>> <mailto:re-wrenches at lists.re-wrenches.org>>,
>> Date:	05/20/2015 11:11 AM
>> Subject:	Re: [RE-wrenches] Fw:  Xantrex C-40 Drifting
>> Sent by:	"RE-wrenches" <_re-wrenches-bounces at lists.re-wrenches.org_
>> <mailto:re-wrenches-bounces at lists.re-wrenches.org>>
>>
>>
>>
>> ------------------------------------------------------------------------
>>
>>
>>
>>
>> The modules are Sunwise 22 V, 40 W modules.  The model number of the
>> modules is SW-S40P SWT.  The are wired in series for a 24 V nominal
>> system.  That would be an mppt voltage of 44 V on a system that
>> directs batteries to absorb at 29.4 volts. I'm not sure what the NOCT
>> voltage would be, but it would seem like it would be an ok fit?
>>
>> I think you are on the right track with the MPPT charging graph. The
>> CC likely allows pulses of full charge to hit when the batteries are
>> at their maximum set point voltage.
>>
>> Would a very short pulse of high voltage be a problem of a VRLA
>> battery? Could any significant gassing take place?
>>
>> Thanks,
>>
>> Drake
>>
>>
>>
>> At 06:04 PM 5/19/2015, you wrote:
>> Hi:
>>
>> We haven't changed anything the in C40.  The essence of my idea was
>> that perhaps the "trouble" systems are the ones which have much higher
>> module Voc versus battery Vfloat.
>>
>> JARMO
>> _____________________________________________________________________________________*
>>
>> Jarmo Venalainen*  | *Schneider Electric **  |  Xantrex Brand*  |
>> *CANADA*  | *Sales Application Engineer* *
>> Phone:* _+604-422-2528_ <tel:%2B604-422-2528> | *Tech Support:*
>> _800-670-0707_ <tel:800-670-0707> | *Mobile:* _+604-505-0291_
>> <tel:%2B604-505-0291>*
>> Email:* _jarmo.venalainen at schneider-electric.com_
>> <mailto:jarmo.venalainen at schneider-electric.com> | *Site:*__
>> <http://www.xantrex.com/>_www.Xantrex.com_
>> <http://www.xantrex.com/>__  | *Address:* 3700 Gilmore Way, Burnaby,
>> BC V5G4M1 _
>> _[] <http://www.xantrex.com/>__[] <https://www.facebook.com/Xantrex>[]
>> <https://twitter.com/Xantrex>[] <https://twitter.com/Xantrex>
>>
>>
>> *** Please consider the environment before printing this e-mail
>>
>>
>>
>> From:Ray Walters <_ray at solarray.com_ <mailto:ray at solarray.com>>
>> To:RE-wrenches <_re-wrenches at lists.re-wrenches.org_
>> <mailto:re-wrenches at lists.re-wrenches.org>>,
>> Date:05/19/2015 11:00 AM
>> Subject:Re: [RE-wrenches] Fw:  Xantrex C-40 Drifting
>> Sent by:"RE-wrenches" <_re-wrenches-bounces at lists.re-wrenches.org_
>> <mailto:re-wrenches-bounces at lists.re-wrenches.org>>
>>
>>
>>
>>
>> Hi Jarmo;
>>
>> Early solar systems actually tried to use the principle of matching
>> array Vmpp to battery voltage  in lieu of charge controllers.  The
>> biggest issue is that when it is is hot the module voltage can drop
>> below the battery voltage needed, and when its cold the voltage will
>> still be too high.   Batteries were either over charged or never
>> reached full charge depending on the conditions.
>> I've used the C40 successfully for decades, so I'm wondering if the
>> circuitry changed recently, or if different tolerance components were
>> substituted that may be causing the drift?
>>
>> Thanks,
>> R.Ray Walters
>> CTO, Solarray, Inc
>> Nabcep Certified PV Installer,
>> Licensed Master Electrician
>> Solar Design Engineer_
>> __303 505-8760_ <tel:303%20505-8760>
>> On 5/19/2015 10:31 AM, _Jarmo.Venalainen at schneider-electric.com_
>> <mailto:Jarmo.Venalainen at schneider-electric.com>wrote:
>> Hi:
>>
>> I didn't know that there were systems out there where a PWM charge
>> controller such as the C-40 was producing an unhealthy, high battery
>> voltage. Since there are, I may have a possible explanation.
>>
>> The C-series and other PWM type charge controllers operate by PWM
>> whereby they very very quickly connect/disconnect the solar module to
>> the battery bank.  The amount of time which the module is connected to
>> the array is the PWM on-period.  These controllers do not have the
>> ability to "smooth out" the output voltage.  All they can do is apply
>> the full module voltage OR not a
>>
>
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